The Somerset herald. [volume] (Somerset, Pa.) 1870-1936, 1887-08-24
use np all the fat that the clans eaten

would have made.
The correspondents reference tothe IT,
dal wave entering Long Island Sound and
the Narrows at one instant suggests an
other cause for variation in the heights
aud dufations Of tides. The tidal wave
enters the Sound At Block Island AT
about the time that it enters the lower
l,ay at Sandy Hook mot the Narrows),
sometimes two minutes later. One wave
sweeps up the Sound and the other
through the Narrows. the upper bay, East
River and Hell Gate. One has fairly
unobstructed course, and the other tor
tuous one. They meet at various points
between Astosia and Throg's Neck 1t Is
said that if dam could be built across
| Hell Gate where the tall electric light
tower stands the water on one side OF the
dam wonld sometimes be five feet higher
than on the other. This would be due 10
{ the fact that one high tide had got there
long before the other. Sometimes one
would be ahead, and then again the 9TH
or. We donot know why this Is 80. The
friction of the water on the beds of the
channel partly, but not, wholly. explains
the phenomenon. Ii is partly because of
this friction that the second tidal wave Of
the day was retarded twenty-three min
utes at Sandy Hook and thirty-four min
utes at He'll Gate on a certain day, but
that does not wholly explain it. The Of
ficers Of the Coast Survey are keeping ac-
curate records Of the tides wherever they
are at work, If the appropriations hold
out they viii probably know all about
Tie matter in few years, but many mil
lions Of observations viii have TO be tax
en- and considered first
There is Of course tidal wave in the
seas below the Cape of Good Hope as
well as elsewhere in The ocean, but this
great Southern wave sweeps into the
south Atlantic unobstructed, while the
heavenly bodies have to get up, as one
may say, new wave in the Atlantic af-
ter passing over the Eastern continent
This new wave and that portion of the
! Southern sea wave from around the point
of Africa, which is DETECTED upon the
coast Of south America, interfere with
each other. Very likely the wave from
the South modifies the tide at New York.
Il certainly modifies ihe tide at Calves
ton, Texas. Galveston has only one tide
a day instead of two. 1t is said that one
tidal wave sweeps into the Gulf of Mexi-
co around the point Of Gucatan, and an
other around the point Of Florida. The
two reach Galveston At different hours, -
that one neutralizes the other entirely al
one hour for high tide and nearly so at
the next the only rise Of the day being
due TO the fact that the intervals of the
two waves are not the same.
One very interesting and in some plac-
es dangerous tidal phenomenon is called
the bore. Owing to the shape and posi-
ton of some estuaries the tidal wave
comes in as a huge, foam-capped breaker
that travels with mighty roar and car
ries destruction to all frsil objects that
happen to be in rs path. The bore Is
seen in its greatest glory perhaps in the
| Amazon river. On account of the course
and shape and length of this estuary it
happens that as many as eight high tides
maybe travelling up the stream at once,
of which five may be roaring bores. These
bores are from II TO Is feet high.
There is difference between a tidal wave
and tidal current, although most people
confound the two. The current is due TO
the wave, Of course, but the tide NAV be
rising in place when no current is visi-
bic. That is, the surface of the water
may be rising while there is no percepti
bic current running in. In fact, the wa-
ter in New York harbor is often rising
when the surface current is running out,
and vice versa. This is due To undercur-
rents. The water on the surface runs one
way, while below it more powerful cur
| rent is running the other. In the Chesa
peake bay the crest Of the high water
wave travels up the bay at the rate Of
fifteen miles an hour, while the current
is nowhere more than one mile an hour.
The tidal wave enters this bay smoothly
and quietly, but why it should do 50
there when il makes such a terrible fuss
running up the Amazon is not fully un-
| derstood. The difference in the form of
the shores does not explain it. There is
great volume of water pouring out Of
the Amazon. while but little pours out of
the Chesapeake. This may partly ex
plain the difference, because ordinary
rollers always break in the mouth of Ia
river when the current out is strong.
While the heaping up of the water is
due TO the attraction of the moon and
sun, the water at any point is not highest
when those bodies pass the plane of the
places meridian. High water comes
along good deal later, as rule. The
interval varies with the time in the
month, but not, as rule very much.
This interval is called the establishment
of the port, something that is talked of a
great deal in old books of discoveries Of
unknown seas. When a new port was
discovered the discoverer would note the
hour at which the moon passed the me
ridian AT full or new moon, and then the
hour of the high tide that followed. This
interval was communicated to the world. (
50 that the next navigator to reach that
vicinity could tell when TO expect nigh |.
tide by simply observing when the moon
crossed the meridian. He had only to
add the number of hours in the interval
to the hour at which the moon crossed I
the meridian, and he had the hour of
high time near enough for the practical
purposes of that age. II is to be noticed /
also that the spring tides do not. occur the .
day at which the moon is full or new,
but anywhere from twelve TO thirty-six .
hours later. II seems 10 take the moon I
that long TO TO fully exert It's powers, but 4
why the interval should be twelve hours 4
at one place and thirty-six at another is 1
not understood yet. There are quite .
lot of books that treat of the subject, but /
no two agree, and much study of them is .
wearisome. Still, enough is definitely .